PARIS — There’s a military mood in the air, and it’s turning up in a variety of collections, expressed in looks that range from strict interpretations of the idea to much subtler mixes. In the Louis Vuitton collection he delivered on Wednesday, Marc Jacobs came up, of course, with his own spin on the concept, along with other concepts such as long, lightweight dresses and tops, worn bunched up. Here, his officer’s jacket over a flowered skirt. For more on the season, see pages 4 to 7.